Profile grinding or polishing machine



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Patented Sept. 7, 1954 UNITED STATES ATENT QFFICE PROFILE GRINDING OR POLISHING MACHINE Application October 16, 1952, Serial No. 315,141

Claim priority, application Great Britain October 19, 1951 4l Claims.

The invention relates to a profile grinding or polishing machine oi the character described in the speciiication of U. S. Patent No. 2,585,376 and consists in improvements or modifications in the means for effecting and controlling the tilting of the work table.

The object of the invention is to enable the tilting of the work table to be effected by means ensuring a positive and accurate operation according to the prole of the work piece, and to enable such means to be controlled by a device capable of easy adjustment even, if required, while the feed carriage progresses across the machine.

According to the invention hydraulic cylinders are provided for tilting the work table, both up and down, the supply and the exhaust of pressure fluid to and from these cylinders being controlled by a control valve operated by a cam bar on the cross feed carriage, the casing of the control valve being so supported as to reciprocate with the traversing table and to rise and fall correspondingly with the downward and upward tilting movements of the work table.

rhe cam bar is preferably adjustably mounted so that its inclination can be varied, and the means for adjusting it are preferably such as to permit of adjustment even during operation of the machine.

In the accompanying drawings:

Figures l and 2 are respectively a front and side elevation of grinding or polishing machine according to one form of the invention.

Figure 3 is a side sectional elevation on the line 3-3, Figure l showing on a larger scale the control valve, and means for supporting it.

Figure 4 is a plan corresponding with Figure 3.

Figures 5, 6 and 7 are sectional side elevations of the control valve showing the piston valve in diiierent positions.

Figure 8 is a sectional view of a form of adjustable supporting rod for the cam bar.

Figure 9 is a flow diagram.

Figures l and 10a are somewhat diagrammatic representations respectively of one of a pair of rails profiled for use when grinding or polishing, for example, a mould board of a plow; and

Figure ll is a schematic front elevation of the machine showing varying inclinations of the cam bar.

The example illustrated by these drawings is shown applied to a machine of the general character described in the specification hereinbefore referred to and for the sake of clarity certain of the features 0I" the machine are indicated by reference numerals similar to those used for corresponding parts shown in the drawings accompanying that specification, namely, the machine as shown in Figures 1 and 2, comprises a grinding or polishing wheel l fixed on a spindle 2 which is mounted to rotate in a bearing housing 3, pivotally mounted on trunnions 4 in a crotch 5, which is mounted on a stationary column 8 so that it can be raised and lowered initially by suitable means to vary the height of the trunnions 4 and therefore of the pivotal axis of the spindle 2. Normally the spindle 2 is :tree to oscillate about its pivotal axis, suitable means being provided ior raising it with the grinding wheel in an inoperative position at the end of a grinding operation.

The work piece Se is mounted on a work table Eil pivotally mounted on trunnions 36 on brackets lil' fixed to a traversing table 38, which reciprocates or traverses on slides 33 and rollers 4U on a cross feed carriage lll. The traversing table 38 is reciprocated by a hydraulic jack cylinder d2, Figure 2, having a piston rod i4 operatively connected to a bracket 46 Xed to the underside of the traversing table. The cross feed carriage il is supported on V slides 65 on a stationary base lit. Itis led, that is, advanced and retracted in a direction normal to the direction of reciprocation of the traversing table 3S by means which are adapted to eect a slow feeding or advancing movement and a quick return. Suitable means are described in the specification hereinbefore referred to but a double acting hydraulic cylinder :itil is indicated for this purpose. It is fixed on the base and has a piston rod Bill attached to a bracket 3d?. on the underside of the cross feed carriage di.

rThis hydraulic feeding mechanism for the cross feed carriage and means for controlling it do not form an essential feature of the present invention but are described in the specification of co-pending application Ser. No. 315,142 led on even date herewith.

The above description will suffice to render clear the general character of the machine to which the present invention is applied, and an example of which will now be described.

Two double acting hydraulic cylinders 303, Figures l and 2, are mounted to pivot on trunnions 3M in forked brackets 335 which are xed on the brackets 3T. The hydraulic cylinders 303 have piston rods 306 the outer ends 301 of which are pivotally connected with levers 308 which are xed on the trunnions 36 of the work table 34.

Pressure fluid is supplied to and exhausted from the opposite ends of the cylinders 303 by pipes 309 and 3|0, under the control of a control valve generally indicated by the reference numeral 3| I.

The control valve 3|| is carried by a bracket 3|2.

As shown in Figures 3 and 4, the casing 3I3 of the control valve 3| is screwed at 3 |4 and 3|5 to the upper and lower parts of the bracket 3|2 which has slides 3|1 sliding in guides 3|8 which are fixed to brackets 3|9 secured to a bar 320. The bar 320 is xed at its ends to the brackets 31, Figure 1.

The bracket 3 |'2 has an arm 32| pivotally connected by a pin 322 to the upper ends of two links 323 the lower ends of which are pivotally connected by a pin 324 to an arm 325 having a flange 326 screwed to the tilting work table 34.

The valve casing 3|3, Figures 5 to '7, has an inlet port 321 for the supply of pressure fluid, and twoexhaust ports 328 and 329. Pressure fluid from a pump 360 Figure 9 is supplied by a pipe 36| to the port 321. The supply pipe 36| is tted with a relief valve 386 having a return pipe 361 to a sump 365. The pressure fluid exhausted from ports 328 and 329 is led by pipes 362, 363 and 364 (Figure 9) to the sump 365. The casing 3|3 also has ports 330, 330, connected by pipes 3| 0, 3|0, to the lower ends of the hydraulic cylinders 303, and two ports 332, 332, connected by pipes 309, 309 to the upper ends of the cylinders 303.

A reciprocating piston valve 334 has a central piston 335 controlling the inlet port 321, and outer pistons 336 and 331 controlling the exhaust ports 323 and 329 respectively.

A helical spring 338 urges the piston valve 334 downwardly in the casing 3| 3. An operating plunger 339 engages with the lower end of the piston valve 334, protrudes from the lower end of the casing 3|3 and has a roller 340 running on a cam bar 34|. The cam bar 34| is supported by rods 342 which pass through guides 343 on the cross feed carriage 4| and have rollers 344 on their lower ends running on profiled rails 345 on the base 65, for example, as shown in Figures 10 and 11. Each rail 345 may be fitted and secured in a slot 310 in the base 65 by a screw 31|. As a workpiece such as the mould board of a plow has a varying contour, it is desirable that the worktable shall be tilted to ensure that the surface of the mould being ground by the grinding wheel shall be presented so that at all times the surface of the workpiece is normal to the grinding wheel, that is, not only during the traversing strokes of the workpiece but also during the advancing or feeding movements of the feed carriage 4| The piston valve 334 is operated by the varying inclinations of the cam bar 34|, and the cam bar 34| is supported by rods 342 whose rollers 344 run on the proled rails, consequently, the profile of the rails 345 must be determined to suit the profile of the workpiece being ground or polished.

Figures 10 and 10a illustrate a pair of profiled rails 345 suitable for grinding a plow share and mould board, the positions X, Y, Z of the rods 342 representing the feeding in or advancement of the feed carriage 4|. The resultant inclination of the cam bar 34| is schematically shown in Figure 11, the positions X, Y and Z of the cam bar of this ngure representing the inclina- 4 tions of the cam bar when the rods 342 are at the positions X, Y and Z, Figure 10. Thus, the roller 340, which traverses the cam bar 34|, follows the varying inclinations of the cam bar and the piston valve 334 is operated accordingly.

In order to permit of fine adjustment in the length of the rods 342 to vary the inclination of the cam bar 34 the arrangement shown in Figure 8 may be adopted. Such fine adjustment may be necessary to compensate for irregularities in individual Workpieces or when otherwise it would be necessary to raise or lower slightly a rail 345 of the correct profile. This adjustment comprises a screwed sleeve 346 in the upper end of each rod 342, in which sleeve a stem 341 is rotatably mounted, the stem having a fork 348 to receive the cam bar 34| to which it is pivotally connected by a pin 349 passing through a slot 350 in the cam bar. Each rod 342 has a collar 35| on which bears the lower end of a spring 352 housed in the guide 343.

Rotation of the sleeve 346 will vary the length of the rod. The sleeve can be locked after adjustment by a lock nut 353.

The ne adjustment of the cam bar 34| can be effected even during operation of the machine.

The rails 345 may be removable, for exchange with others of different profile or inclination.

In order to prevent back pressure the usual exhaust bleeds are provided at the ends of all the hydraulic cylinders.

In the operation of the machine the roller 340 of the operating plunger 339 of the control valve 3| travels up and down the cam bar 34| as the traversing table 34 reciprocates. The control valve is closed at the end of each stroke of the traversing table so that the tilting of the work table ceases. At the start of each stroke of the traversing table the control valve has to be opened to renew the supply and exhaust of pressure uid to and from the appropriate ends of the hydraulic cylinders, and this open condition has to be maintained during the stroke if movement of the Work table is required.

In order to effect the above operations of the control valve it is necessary that there shall be relative movements between the valve casing and the piston valve at the end and the start of each stroke of the traversing table, and, moreover, that during each stroke of the traversing table the valve casing shall move vertically to maintain its necessary relation to the piston valve. In other words, as the operating plunger is riding up and down the cam bar during the reciprocation and the tilting of the work table, the valve casing must also be moved up and down correspondingly.

Assuming that the traversing table 38 is about to start a stroke from left to right, considered with reference to Figure 1, the control valve will be in the closed condition shown in Figure 5 with the work table 34 in the raised position.

The valve piston 335 has closed the inlet supply port 321 and the valve pistons 336 and 331 have closed the exhaust ports 320 and 329 respectively.

At the start of the stroke of the traversing table 38, the roller 340 moves up the cam bar 34| and the operating plunger 339 begins to raise the piston valve 334 relative to the valve casing 3|3, so that, as shown in Figure 6, the valve piston 335 uncovers the inlet supply port 321, and the valve piston 336 uncovers the exhaust port 328, the valve piston 331 still closing the exhaust port 329. Pressure fluid is thus allowed to flow via ports 321, 332 and pipes 309 to the cylinders 303 and exhaust from the cylinders 303 via the pipes 310 and ports 330, 328 and pipe 362, to begin the tilt of the work table in a clockwise direction with reference to Figure 6. In this figure, the valve is shown fully open for the sake of clearness, but the work table will begin to tilt immediately the valve begins to open. The downward movement of the work table will raise the valve casing 313 so as to compensate for the rising of the piston valve 334 which occurs during the travel of the roller 340 up the cam bar 341, the control valve remaining open to allow fluid pressure to continue the downward tilt of the Work table.

When the traversing table 38 reaches the end of its stroke from left to right with reference to Figure 1, the piston valve 334 ceases to rise, but as the work table 34 continues to tilt downwardly, it continues to raise the valve casing 313 until the valve pistons 335, 336 close the ports 321, 328, as seen in Figure 7, so that the supply and exhaust of pressure iluid to and from the cylinders 303 ceases and the work table 34 is arrested in its downward position.

At the start of a return stroke of the traversing table 38, from right to left, with reference to Figure 1, the piston valve 334 will begin to descend, but the valve casing 313 will remain raised until the valve pistons 335, 331, have uncovered the ports 321, 329, to allow pressure fluid to pass via ports 321, 330 and pipes 310 to the cylinders 303 and exhaust fluid to flow from the cylinders via pipes 309, ports 332, ports 329 and pipe 363. The work table will then begin to tilt upwardly and to lower the valve casing. During the whole of the return stroke, the upward tilting movement of the work table will maintain the control valve in the open condition until the end of the return stroke so long as work table movement is required. The ports will then be restored to the condition indicated in Figure 5, that is, the arrest of the operating plunger 339 but momentary continuance of the lowering of the valve casing 3l3 will result in the closing of the ports and the work table will cease to tilt upwardly.

The pressure of the fluid in the hydraulic cylinders is kept sufiicient to ensure adequate resistance of the work piece to the pressure of the grinding wheel in all positions in which the table is tilted.

The work table 34 is thus tilted downwards by the piston rods 396 and lever 308 until the valve casing 3I3 has been raised relatively to the operating plunger 339 by the work table 34 l acting through the links 323 and bracket 3 I 2, and the piston valve has again closed the ports 321, 328, and 329, Figure 7.

On the return stroke of the traversing table 34 from right to left, the operating plunger 339 rides down the cam bar 34| and the compression spring 339 moves the piston valve 334 to reverse the operation that is to cause the piston rods 306 of the hydraulic cylinders 303 to move in and to tilt the work table 34 upwards; that is, the piston valve moves downwardly so that the central valve piston 335 moves across and uncovers the inlet port 321 to allow pressure fluid to pass to the ports 330 and thence by pipes 310 to the forward or lower ends of the hydraulic cylinders 303. At the same time the lower valve piston 331 opens the exhaust port 329 to allow pressure fluid to exhaust from the upper or rear ends of the hydraulic cylinders 303 through the pipes 309, ports 332 to the exhaust port 329.

Consequently the work table 34 is tilted upwardly as the piston rods 306 move into the cylinders 303.

The work table 34 continues to fall or rise during each traversing stroke of the operating plunger 339 up or down the cam bar 34| until the valve causing 313 has been moved suiiicently by the work table 34, arm 325, links 323, arm 321 and bracket 312, to bring the ports 321, 328 and 329 opposite the valve pistons 335, 336 and 331 respectively, that is to bring the control valve into a neutral position so that both ends of the hydraulic cylinders are closed oi and contain pressure fluid and consequently the work table is held by them in the position to which it has been tilted. Adequate resistance of the work piece to the pressure of the grinding wheel is maintained in all positions in which the table is tilted.

As described above with reference to Figure 8 the degree of tilt of the work table can be varied even during operation of the machine by adjusting the supporting rods 342.

We claim:

1. A grinding machine comprising a base, a grinding wheel journalled on said base, a crossfeed carriage movably mounted on said base, a table mounted on said carriage for traverse movement transverse thereto, a work table pivotally mounted on said traverse table for supporting a work piece in position relative to said grinding wheel, hydraulic cylinder means on said traverse table and connected with said work table for tilting said work table about its pivotal mounting, a control valve for said hydraulic cylinder and including a valve body and a valve member movable in said body, a cam on said cross feed carriage, cam following means engageable with said cam and connected with said valve member to move said valve member relative to said valve body, and means connecting said valve body with said work table to move said body relative to said valve member in accordance with the pivotal movement of said work table.

2. A grinding machine as defined in claim 1 wherein said cam comprises a bar, and means supporting the ends of said cam bar and including means for varying the relative positions of said bar ends during the relative movement between said cam following means and said cam bar.

3. A grinding machine as dened in claim 2 wherein said cam bar supporting means comprises a pair of rails on said base, a pair of guides on said cross feed carriage, and a pair of supporting rods respectively slidably supported in said guides with the one of their ends bearing on said rails and the other of their ends respectively connected with the ends of said cam bar, whereby to vary the position of said cam bar during the relative movement between it and said cam following means.

4. A grinding machine as defined in claim 3 comprising manually operable means for adjusting said rails relative to said base.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,970,000 Dunbar Aug. 14, 1934 2,276,260 Turrettini Mar. 10, 1942 2,485,716 Eberlain Oct. 25, 1949 2,585,376 Dyer Feb. 12, 1952 

